Polychromatic graphic visual display and control system assembly

ABSTRACT

Polychromatic visual display and control system assembly, characterized by a main memory receiving graphic data corresponding to traces of various colors and/or various color portions to be displayed on a polychromatic cathode tube, and a selection system for sequentially selecting one of the various colors and for controlling the read-out from the main memory of all the data corresponding to the selected color such that the display of the traces and/or portions of the traces of each of the various colors is enabled in a sequential manner to form a composite display of the traces of various colors.

[ Dec. 10, 1974 POLYCIIROMATIC GRAPHIC VISUAL DISPLAY AND CONTROL SYSTEMASSEMBLY.

Inventor: Philippe Ligocki, Creteil, France Assignee: CompagnieIndustrielle des Telecommunications Cit-Alcatel, Paris, France Filed:May 18, 1973 Appl. No.: 361,493

Foreign Application Priority Data May 19, 1972 France .1 72.18013 Sept.1, 1972 France 72.31146 US. Cl...-. 340/324 AD, 178/54 CD, 340/1725 Int.Cl. G06f 3/14 Field of Search 340/324 R, 324 AD, 172.5;

References Cited UNITED STATES PATENTS 11/1971 Clark 340/324 AD MEMORYADDRESS REGISTER AUXILIARY MEMORY ADDRESS COUNTER 3,668,686 6/1972Strohmeyer 340/324 AD Primary Examiner-John W. Caldwell AssistantExaminer-Marshall M. Curtis Attorney, Agent, or Firm-Craig & Antonelli[57] ABSTRACT Polychromatic visual display and control system assembly,characterized by a main memory receiving graphic data corresponding totraces of various colors and/or various color portions to be displayedon a polychromatic cathode tube, and a selection system for sequentiallyselecting one of the various colors and for controlling the read-outfrom the main memory of all the data corresponding to the selected colorsuch that the display of the traces and/0r portions of the traces ofeach of the various colors is enabled in a sequential manner to form acomposite display of the traces of various colors.

14 Claims, 2 Drawing Figures RECORD R A 1 POLYCHROMATIC GRAPHIC VISUALDISPLAY AND CONTROL SYSTEM ASSEMBLY mathematical curves to be observedon a screen.

Various data relating to craft moving in the region of space consideredand concerning, more particularly, their position, their identity, theirspeed or their altitude, in the case of aircraft, are transmitted to theobserver installation, for example by a radar or other deteetion ortelemeasuring devices. The vectors which are to be traced on thepanoramic indicator screens are intended, for example, to indicate thedirection and the speed of the craft, or of the cartographic elements.These vectors are linked together and thus form broken lines orpolygonal contours. They have well-defined origins and ends. It isparticularly interesting to be able to observe the traffic of thesevarious craft according to traces of different color, in order to avoidany possible confusion between the trajectories of the various craft.

Known devices enabling such results generally comprise a polychromaticcathode tube whose screen is suitable for receiving traces of severalcolors, these traces being renewed in successive cycles;

a main memory comprising a memory block, an address register and anoutput register, from which are extracted the graphical data receivedfrom a calculator or computer (this data is recorded by the memory blockand classified according to its address in that block and it concernsthe directing parameters and the color of each vector forming a part ofthe polychromatic traces);

a data processing means or element for enabling the generation of traceson the screen of the cathode tube 'in accordance with the outputregister of the main memory;

a vector generator controlled by the data processing element andsuitable for affecting the deflection of the cathode beam so as to maketraces appear on the screen (Generally, the vector generator isconnected with a character generator enabling characters to be made toappear on the screen); and

means for causing changes in color of the vectors, these means beingcontrolled by the control block and also form a part of the devices.

Generally, the polychromatic visual display assembly is equipped with acathodic penetration tube which enables a polychromatic addingsynthesis, controlled by the energy in the electrons of the beam. Thatis, by switching the acceleration voltage of the electrons, the color onthe screen is changed. Such voltage switching requires high power, forexample, with a conventional switching device,-the average powerdissipated is on the order of 100 watts for a cathode tube having adiameter of 40 centimeters and with a switching time not exceeding amillisecond.

The loss of time, when tracing figures, which results from such relativeslowness, causes stresses for programming pictures. Indeed, only 25milliseconds at the most are available for tracing the picture, sincethe light revival frequency must not go below 40 Kc/s as this wouldcause a disagreeable flickering. lf the color is not counterbalanced bya reduction in the representing capacity, the total duration assigned tothe color switching operations during a cycle must remain small withrespect to theperiod of each cycle of traces. With a switching time inthe order of a millisecond, this necessitates a grouping together of theelements of the picture according to color to be effected by programmingin order to require of the visual display assembly only the minimum offour color changes per picture (in the case where the polychromaticvisual display assembly is a four-color assembly, for example).

The programming requirement is, when analized, a very serious matter. Inthe first place, it makes the rearranging and transferring of a newvisual display program compulsory for the least change in color of asimple vector of the traces, since the place of each vector in the mainmemory depends on its color. If the link with the computer has a lowoutput, the operator must, wait a long time for the complete message tobe transmitted. What is more serious is that the rearranging requires agreat amount of work by the calculator. Considering, for example, acurve traced in a certain color by means of a sequence of vectors; thesimple changing of the color of a small part of the curve requires thebreaking of that sequence and hence, not only transferring the elementin question to another memory zone, but also inserting two furtherpositioning instructions, the one at the outset of the element which haschanged color, and the other at the resumption, on the curve of theinterrupted chain.

There are even more serious problems. For example, performing graphicsystems generally enable the simultaneous display of several pictures.Thus, it is possible to feed four cathode units, for example, withdistinct pictures. The memory, the vector generator, the charactergenerator and the connected circuits are common and used on atime-sharing basis. In principle, the four pictures are tracedsuccessively, extinguishing, for each, the beams of the screens whichare not concerned. The program requirement for grouping togetheraccording to color, necessitates that with multiscreen systems, the fourpictures are dissociated and that at the least change made to oneof thepictures, the complete message of the four pictures must be reorganizedby the computer and transferred to the assembly.

A programming facility afforded to known assemblies is the subprogramcall instruction by means of which a picture element capable of beingrepeated needs to be written only once, in a corner of the memory, fromwhere it may be called through the main program. It is quite evidentthat the sorting out according to color requirement prevents any changein color within a sub-program. These sub-programs must be written in anachromatic way and will compulsorily be visually displayed inmonochromatic form.

With regard to power dissipation problems in the color switchingelements, a known device enables very fast switching without permanentpower dissipation to be ensured. The duration of the color changes maythus be reduced to 50 microseconds. In a great number of applications,that solution is satisfactory and enables the color to be treated as avariably selected parameter, in the same way as the brightness of thetraces, for example. Unfortunately, one requirement limits, at present,the number of color changes allowed per picture. Technologicalimperatives limit the average power exchanged between the colorswitching device and the reactive charge which the anode of thecathodetube represents. In present technology, that limit is reached at colorchanges per cycle of traces and per screen (the screens not concernedremaining at rest). That this solution it is not only necessary torecord a list for the sorting out of the vectors according to color, butmoreover, it is necessary to:

l. Dissect each assembly of traces into isochromatic elements orvectors. That is, determine all the elements whose color is liable to bemodified.

2. Make the trace of each isochromatic element thus determinedpractically autonomous, that is, independent from what may be tracedbeforehand. Thus, not

only the color, which is the cause of that dissociation, but all theother parameters, as well as the original positioning of each vector,must be specified at the beginning of each element.

3. Organize in a quite particular manner the visual display program.That is, each isochromatic element must be recorded in the form of anachromatic subprogram and the main program then takes the form of a listof sub-programs, each being preceded by the indication of its color. Ifthere are four distinct colors, these requirements then being satisfied,the main program must. be read four times in succession, by cycle oftraces, that is, calling only the sub-programs which are in theprocessed color.

The part of the requirements imposed by the above solution presentproblems when analized. For example, considering'a curve traced quitenaturally by a sequence of smallvectors, if it isv required to be ableto show the operator any element of the curve and to modify its color,this simple method of tracing is no longer possible, since eachelementary vector must be preceded by a positioning and thespecification of its color. It must, moreover, be transmitted in theform of a sub-program with the jump and return to main programinstructions which this entails. This is the equivalent of saying thatit is an impossible task. It is therefore possible to have doubts aboutthe advantage of a solution which sacrifices, to avoid a programmingrequirement which might be troublesome but not impossible to overcome,the true possibilities of using color.

It is therefore an object of the present invention to avoid thesevarious programming and technologically limiting requirements.

In accordance with the present invention, there is provided apolychromatic graphic visual display assembly comprising:

a polychromatic cathode tube whose screen is suitable for receivingtraces having portions of various colors, these traces being renewed insuccessive cycles;

a main memory comprising a memory block, an address register and anoutput register from which the graphic data received from a computer areextracted, the main memory being suitable, for each portion of traces,for recording a group' of data items relating to that portion, the groupof data items being classified in the memory in a group of addresses,the first of these data items relating to the color of the portion andbeing classified at a first address, called the color address, in thegroup of addresses, the other data items relating to the parameters ofthe vectors constituting the portion being classified at the followingaddresses in the group of addresses;

a data processing element for enabling the generation of the traces onthe screen of the cathode tube, in accordance with the output of theoutput register;

a vector generator and a character generator controlled by the dataprocessing element and capable of influencing the deflection of thecathode beam so as to make traces and characters appear on the screen;

means for causing changes in color of portions of the traces, the meansbeing controlled by the control block; and

the assembly being characterized in that it comprises a color changeaddress selecting element controlled by the memory block and its addressregister, the selecting element listing the color addresses of thevarious groups and recording the corresponding color data, and theselection element being capable of controlling the reading of the mainmemory, so as to extract successively from that memory the datacorresponding to the groups of addresses of the main memory containingidentical color change data.

These and other objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing, which shows, forpurposes of illustration only, two embodiments in accordance with thepresent invention, and wherein:

FIG. 1 is a schematic block diagram illustration of an embodimentaccording to the present invention; and

FIG. 2 is a schematic block diagram illustration in another embodimentaccording to the present invention.

Referring now to the drawings wherein like reference numerals areutilized to designate like parts throughout the several views, thevisual display assembly shown in FIGS. 1 and 2 are provided with apolychromatic cathode tube 1 whose screen 2 is suitable for receivingtraces of several colors, these traces being renewed in successivecycles. A main memory is also provided and includesa memory block 3, anaddress register 4 and an output register 5. The geographical dataconcerning the directing parameters and the color of the vectors forminga part of the polychromatic traces are received from a calculator orcomputer 6 by the block 3. This data is classified according to itsaddress by means of the address register 4. A data processing element 7for enabling the generation of the traces and controlling the traces onthe screen 2 of the cathode tube 1 is connected to the output register 5and controlled thereby. A vector generator 8 and a character generator 9controlled by the processing element 7 and suitable for influencing thedeflection of the cathode beam are provided so as to make traces andcharacters appear on the screen. These vector and character generatorscontrol the horizontal deviation plates 10 and vertical deviation plates11 by means of analog voltages supplied by a binary-to-analog convertor12. It has been supposed, by way of an example, that one of thehorizontal deviation plates 13 and one of the vertical deviation plates14 are brought to a fixed reference potential.

The assembly comprises, also, means 15 for causing changes in color ofthe traces. These means consist of a switching element for the highvoltage applied to the cathode 16 of the cathode tube 1 and they arecontrolled by the element 7. It has been supposed, by way of an example,that the wehnelt 17, as well as the anode 18 of the cathode tube, isbrought to the fixed reference potential. v

Lastly, the assembly includes an address selection element or system 19for selecting by change in color, and controlled by the memory block 3,by the address register 4 of the main memory and by the processingelement 7. The selectionelement is controlled so as to receive, from thememory block 3 and from its address register 4, the data relating toeach change in color of the traces and enables all the addresses in themain memory where color change data is stored to be listed. Theselecting element 19 then controls the address register 4 of the mainmemory, so that, for each cycle of traces of several colors, the dataitems extracted from the main memory is classified into several groupsof addresses comprising identical color change data. Thus, in theexample of a chosen embodiment, for which the visual display assemblyenables red, orange, yellow and green traces to be effected, theselection element19 which has received data concerning the address andthe color of the various color changes contained in the mainv memory,controls the reading of the main memory, so that, for example:

Only data concerning the red-colored traces are ex-- tracted from themain memory. That is, only the addresses preceded by a change in the redcolor will be selected and consequently occupied by data concerningred-colored traces. For that cycle of traces, the redcolored traceseffected through the data processor 7, the vector generator 8, thecharacter generator 9 and the switching system will appear in the firstinstance on the screen.

The processing then continues by means of element 19 for selection bycolor change address, in an identical manner for the other colors forthe cycle of traces considered. That is, all theorange-colored traces,then all the yellow-colored traces and lastly all the greencoloredtraces are formed.

The operation of the selection element 19 will be better understood byway of the following description. The selection element includes anauxiliary memory 20 controlled by the memory block 3 and by the addressregister 4 of the main memory. It is this auxiliary memory 20 whichrecords the address and the color of each change in color in a samecycle of traces. There is also provided an address sorting out system 22which includes a reference element 24 capable of sending out,successively, for each cycle of traces and for each color of traces, areference signal characteristic'of that color. The reference element maybe a counter. having four states, in the case, for example. of a visualdisplay system having four colors of traces. The counter will be placedin the first, second, third and fourth states, respectively for red,orange, yellow and green, during a cycle of traces. lt will thereforesupply, at the output, successively, four reference signals, each ofthese signals relating to a color of the traces. The counter mayreceive, on one of its inputs 25, a signal for resetting to zero at theend of the cycle, coming from the auxiliary memory 20 through areferencing element 26. The reference element 24 receives, on one input27, a signal indicating the end of a reading pass of the auxiliarymemory, each time a group of addresses concerning a same color isexhausted. The end of reading pass signal causes the change in states ofthe counter.

The color change address sorting out system also includes a colorcomparator 28, which receives, on one input 29, the reference signal ofthe reference element 24. The comparator receives, simultaneously, onanother of its inputs 30, the color signals sent out by an output of theauxiliary memory 20, relating to the various changes in color listed inthe auxiliary memory and coming into play during a cycle of traces. Ifthe color signal corresponds, at the instant considered, to thereference signal 29, a signal which may be qualitied, for example, as asuccessful test signal, appears at the output 31 of the comparator andcauses the blocking of an AND gate 32, one of whose inputs receivespulses from a clock 37. If, on the other hand, the color signal 30 doesnot correspond to the reference signal, a negative test signal appearsat the output 32 of the comparator and makes the AND gate 32 conductive.An address counter 33 for the auxiliary memory 20 is connected by aninput 34 to the output of the gate 32, Reading or recording in theauxiliary memory is effected through a recording and reading element 23,controlled by an output 39 of the data processor 7.

The selection system 19 enables the reading of the contents of theauxiliary memory 20 by the sorting out of the groups of color changeaddresses. Thus, at the f instant considered in the example, only thesuccessive addresses in the main memory preceded by a change in the redcolor, then the addresses preceded by a change in the orange color, theaddresses preceded by a change in the yellow color, and then in thegreen color, will be retained for the traces. For each address of theauxiliary memory, for which a successful test signal has been sent outby the comparator 28, there appears at an output of that auxiliarymemory corresponding to that address, an operand which enables thereading of the main memory at the address considered. In a firstoperation phase of the visual display assembly, the graphic data, for acycle of traces coming from the calculator, are charged in the mainmemory. In a second operation phase, the charging of the auxiliarymemory 20 is effected by the data concerning the address and color ofeach color change, a recording order having reached an input 35 of thatmemory. Lastly, the third operation phase is the auxiliary memoryreading phase, controlled by the selection system 19, as has previouslybeen described. Each time an address forming a part of a same colorchange group in the auxiliary memory is selected, an operand appears atone of the corresponding outputs of the buffer 21 of that memory, thiscausing the graphic data contained at that address to be extracted fromthe main memory. The trace corresponding to that data then appears inthe color of the color change group selected by means of the referenceelement 24',

If a successful test signal is applied at the output 31 of thecomparator, there is no signal at the input 34 of the address counter33. In that case, the address counter 33 does not change states, thiscausing the appearance of an operand at an output corresponding to theaddress considered in the auxiliary memory and thus, the reading of thecontents of the main memory 3 at the address considered, when the input36 of the address register of the main memory has received the readingsignal corresponding to that address. A trace corresponding to the datacontained at that address of the main memory is then effected on thescreen in the color determined by the reference element 25 affecting theswitching element 15.

If a negative test signal appears at the output 31 of the comparator 28,this is because the color comparison test is unsuccessful, the colorsignal reaching an input 30 of the comparator not corresponding to thereference signal, the gate 32 then supplies a pulse to the addresscounter 33 which changes states and thus causes the passing to thefollowing address of the auxiliary memory while a new comparison of thecolor signal with the reference signal is established. Comparison testsare thus effected at the successive addresses of the auxiliary memoryuntil an address where a successful comparison test may be establishedis detected, this causing the appearance of a new operand on an outputof the auxiliary memory and the subsequent reading of the correspondingaddress in the main memory.

According to FIGS. 1 and 2, the assembly therefore enables the .tracesto be effected separately according to successive colors, during acycle. In the case of a four-color system, the auxiliary memory ispassed through four times, each pass corresponding to a color. Theprogramming requirements relating to the colors are thus avoided and thecolor switching system does not operate in prohibitive switching speedconditions. With the color change sorting out system, there is no longerany limit in the number of changes in the colors of the traces. Thesystem operates without modification of the aspect of the messagetransmitted by the calculator.

HO. .2 illustrates another embodiment of the present invention which isintended, moreover, to avoid programming requirements relating to theoperating of the spot when there are color changes. In the visualdisplay assembly in FIG. 2, the address register 4 is forced by thecalculator or computer 6, at the beginning of the transfer, towards thememory block 3 at the address considered and is incremented at each wordof the graphic message. The selection element 19 is moreover controlledby the binary outputs 38' and 40 of the assembly 12 comprising abinary-to-analog converter supplying the analog control voltages of thehorizontal deviation plates and vertical deviation plates 11. Thus, foreach color change address, the data concerning the positioning of thelight spot which generates the traces from each color change, aresupplied to the selection element 19, which records them. Thecontrolling of the selection element 19 by the binary outputs 38 and 40of the assembly 12 is applied to the auxiliary memory which records,besides the address and the color of each change in color in a samecycle of traces, the data concerning the position of the light spot atthe instant of the change in color.

In operation, the selection element 19 which has received dataconcerning the address, color, various changes in color and the dataconcerning the positioning of the spot when the color changes, containedin the main memory, will control the reading of the main memory so that,for each cycle of traces having the same color, all the traces of thatcolor are then effected by selection, in the main memory, of the addresspreceded by a change in that color, the data concerning the coordinatesof the light spot being extracted from 6 l the main memory at the sametime as the data concerngramming requirements relating to thepositioning of the spot are thus avoided due to the extra informationsupplied by the auxiliary memory for each change in color, besides theaddress and the color in the main memory, the coordinates of the spot atthe instant of the change in color are shown. These coordinates, at eachchange in color, are calculated by the data processing element duringthe original reading cycle which is used for seeking color changeaddresses. During that original scanning of the main memory, the variousinstructions are carried out as in a normal cycle of traces, but thespot remains extinguished as long as the charging of the auxiliarymemory is effected. During that scanning, each time there is a change incolor, the various data concerning the address and the color of thechange in color is recorded in the auxiliary memory, but moreover, it iseasy, at that instant, to record, also, in the auxiliary memory, dataconcerning the coordinates of the light spot when that change in colortakes place.

During trace presentation cycles, the auxiliary memory is scanned andthe isochromatic assemblies are traced by successive colors;nevertheless, before the trace of each assembly, the light spot ispositioned according to the data recorded in the auxiliary memory. If,at a given instant, a block of traces forming a part of an isochromaticassembly is analyzed in the main memory, then traced and if a colorchange instruction then appears, this indicates the end of theisochromatic block. This is interpreted by the data processing elementas a reading order at the outgoing address of a block of the same colorin the auxiliary memory.

While I have shown and described only two embodiments in accordance withthe present invention, it is understood that the same is not limitedthereto but is susceptible of numerous changes and modifications as areknown to those skilled in the art, and we therefore do not wish to belimited to the details shown and described herein but intend to coverall such changes and modifications as are encompassed by the scope ofthe appended claims.

What is claimed is:

1. Polychromatic graphic visual display assembly comprising:

a polychromatic cathode tube having a screen for receiving traces havingportions of various colors, the traces being renewed in successivecycles;

a main memory means including a memory block, an address register and anoutput register from which graphic data items entered into the memoryare extracted, the main memory means for each portion of tracesrecording a group of data items relating to that portion, the group ofdata items being classified in the memory means in a group of addresses,the first of the data items relating to the color of the portion andbeing classified as a first color change address in the group ofaddresses, the other data items relating to the parameters of thevectors constituting the portion being classified at following addressesin the group of addresses;

data processing means for enabling the generation of the traces on thescreen of the cathode tube in response to the output register;

vector generator means and character generator means responsive to thedata processing means for influencing a cathode beam deflection controlelement means so as to make traces and characters appear on the screen;

means for causing changes in color of the portions of traces in responseto said data processingmeans; and

color change address selecting means responsive to said memory block andsaid address register thereof for listing the color change addresses ofthe various color groups and recording the corresponding color datathereof, the color change address selecting means selecting in sequenceone of the various colors and controlling the reading of the main memorymeans for extracting successively from the main memory means all of thedata corresponding to the groups of addresses of the main memory meanscontaining identical color data for the selected color so as to extractthe data corresponding to the various colors in sequence.

2. Visual display assembly according to claim 1, wherein the colorchange address selecting means includes auxiliary memory meansresponsive to the memory block and theaddress register for listing thecolor change addresses and recording the corresponding color data, andcolor change address sorting system means controlling the auxiliarymemory means to sort out the addresses in the auxiliary memory meanswhich contain identical color data at the reading outputs of theauxiliary memory means and for controlling the reading inputs of themain memory means.

3. Visual display assembly according to claim 1, wherein the cathodebeam deflection control element means provides an output of digitalsignals indicative of light spot positioning data on the screen of thecathode tube, the color change address selecting means being responsiveto the digital signals for listing for each color change address thelight spot positioning data generating the traces from each colorchange, the color change address selecting means controlling the readingof the main memory means to extract the corresponding light spotpositioning data from the main memory means at the same time as theextraction of the data of each color change.

4. Visual display assembly according to claim 1, wherein the digitalsignals are binary signals.

5. Visual display assembly according to claim 4, wherein the colorchange address selecting means comprises:

auxiliary memory means responsive to the memory block, the addressregister and the outputs of the cathode beam deflection control elementmeans for listing the color change address and for recording thecorresponding color change and positioning data; and

color change address sorting system means controlling the auxiliarymemory means to sort out the addresses in the auxiliary memory meanswhich contain identical color data at the reading outputs of theauxiliary memory. means and for controlling reading inputs of the mainmemory means.

6-. Visual display assembly according to claim 2, wherein the colorchange address sorting out system means comprises:

reference element means for providing successive outputs for each cycleof traces and for each of the colors of a reference signalcharacteristic of the color;

color comparator means for comparing, at each instant, the referencesignal with a color change signal provided at one of the outputs of theauxiliary memory means, the color change signal being characteristic ofthe color change data existing in the auxiliary memory means in thecolor address corresponding to the output at the instant, the comparatorproviding an output of one of a positive test sig nal when the colorchange signal corresponds to the reference signal and of a negative testsignal when the color change signal does not correspond to the referencesignal;

an address counter for the auxiliary memory means;

incrementing means responsive to the comparator means for providing anoutput to the address counter of the auxiliary memory means, theincrementing means incrementing the said address counter in response toa negative test signal, the auxiliary memory means providing at one ofthe reading outputs thereof an operand signal when a positive testsignal is obtained for the color address corresponding to such output,the operand signal controlling the main memory means so that a tracecorresponding to the data contained at the corresponding address in themain memory means is effected on the screen;

7. Visual display assembly according to .claim 6,

wherein the reference element means is a counter capable of changingstates for each cycle of traces in ac- ,cordance with the number ofcolors in each of the cycles.

8. Visual display assembly according to claim 7, wherein theincrementing means includes an AND gate having one input connected tothe output of the com parator means and another input connected toreceive clock pulses.

9. Visual display assembly according to claim 5, wherein the colorchange address sorting out system means comprises:

reference element means for providing successive outputs for each cycleof traces and for each of the colors of a reference signalcharacteristic of the color;

color comparator means for comparing, at each instant, the referencesignal with a color change signal provided at one of the outputs of theauxiliary memory means, the color change signal being characteristic ofthe color change data existing in the auxiliary memory means in thecolor address corresponding to the output at the instant, the comparatorproviding an output of one of a positive test signal when the colorchange signal corresponds to the reference signal and of a negative testsignal when the color change signal does not correspond to the saidreference-signal;

an address counter for the auxiliary memory means;

incrementing means responsive to the comparator means for providing anoutput to the address counter of the auxiliary memory means, theincrementing means incrementing the said address counter in response toa negative test signal, the auxiliary memory means providing at one ofthe reading outputs thereof an operand signal when a I positive testsignal is obtained for the color address corresponding to such output,the operand signal controlling the main memory means so that a tracecorresponding to the data contained at the corresponding address in themain memory means is effected on the screen.

10. Visual display assembly according to claim 9, wherein the referenceelement means is a counter capable of changing states for each cycle oftraces in accordancewith the number of colors in each of the cycles.

11. Visual display assembly according to claim 10, wherein theincrementing means includes an AND gate having one input connected tothe output of the comparator means and another input connected toreceive clock pulses.

12. Graphic visual display assembly comprising:

polychromatic cathode tube means for displaying a picture composed oftraces of various colors in accordance with binary data items suppliedby a computer in groups of data items, each group defining successivetraces having the same color;

main memory means for recording the groups of data items at successivegroups of addresses wherein the first address is the color data item ofthe corresponding traces;

processing unit means responsive to the main memory means for generatingsignals for controlling the cathode tube means in accordance with datareadout from the main memory means; and

selection circuit means for sequentially selecting one of the variouscolors and for controlling the readout from the main memory means of allthe groups of data items preceded by the color data item of the selectedcolor, the data read-out being supplied to the processing unit means forenabling the display, one color after another, of the traces having thesame color to form a composite picture.

13. A visual display assembly according to claim 12, wherein theselection circuit means includes an auxiliary memory means for recordingthe color addresses and recording the corresponding color data.

14. A visual display assembly according to claim 13, wherein theselection circuit means also includes color sorting means forcontrolling the auxiliary memory means to sort out the addresses in thesuxiliary memory means which contain identical color data at the readingoutputs of the auxiliary memory means and for controlling the readinginputs of the main memory means in accordance therewith.

* l l l

1. Polychromatic graphic visual display assembly comprising: apolychromatic cathode tube having a screen for receiving traces havingportions of various colors, the tracEs being renewed in successivecycles; a main memory means including a memory block, an addressregister and an output register from which graphic data items enteredinto the memory are extracted, the main memory means for each portion oftraces recording a group of data items relating to that portion, thegroup of data items being classified in the memory means in a group ofaddresses, the first of the data items relating to the color of theportion and being classified as a first color change address in thegroup of addresses, the other data items relating to the parameters ofthe vectors constituting the portion being classified at followingaddresses in the group of addresses; data processing means for enablingthe generation of the traces on the screen of the cathode tube inresponse to the output register; vector generator means and charactergenerator means responsive to the data processing means for influencinga cathode beam deflection control element means so as to make traces andcharacters appear on the screen; means for causing changes in color ofthe portions of traces in response to said data processing means; andcolor change address selecting means responsive to said memory block andsaid address register thereof for listing the color change addresses ofthe various color groups and recording the corresponding color datathereof, the color change address selecting means selecting in sequenceone of the various colors and controlling the reading of the main memorymeans for extracting successively from the main memory means all of thedata corresponding to the groups of addresses of the main memory meanscontaining identical color data for the selected color so as to extractthe data corresponding to the various colors in sequence.
 2. Visualdisplay assembly according to claim 1, wherein the color change addressselecting means includes auxiliary memory means responsive to the memoryblock and the address register for listing the color change addressesand recording the corresponding color data, and color change addresssorting system means controlling the auxiliary memory means to sort outthe addresses in the auxiliary memory means which contain identicalcolor data at the reading outputs of the auxiliary memory means and forcontrolling the reading inputs of the main memory means.
 3. Visualdisplay assembly according to claim 1, wherein the cathode beamdeflection control element means provides an output of digital signalsindicative of light spot positioning data on the screen of the cathodetube, the color change address selecting means being responsive to thedigital signals for listing for each color change address the light spotpositioning data generating the traces from each color change, the colorchange address selecting means controlling the reading of the mainmemory means to extract the corresponding light spot positioning datafrom the main memory means at the same time as the extraction of thedata of each color change.
 4. Visual display assembly according to claim1, wherein the digital signals are binary signals.
 5. Visual displayassembly according to claim 4, wherein the color change addressselecting means comprises: auxiliary memory means responsive to thememory block, the address register and the outputs of the cathode beamdeflection control element means for listing the color change addressand for recording the corresponding color change and positioning data;and color change address sorting system means controlling the auxiliarymemory means to sort out the addresses in the auxiliary memory meanswhich contain identical color data at the reading outputs of theauxiliary memory means and for controlling reading inputs of the mainmemory means.
 6. Visual display assembly according to claim 2, whereinthe color change address sorting out system means comprises: referenceelement means for providing successive outputs for each cycle of tracesand for each of the colors of a reference sigNal characteristic of thecolor; color comparator means for comparing, at each instant, thereference signal with a color change signal provided at one of theoutputs of the auxiliary memory means, the color change signal beingcharacteristic of the color change data existing in the auxiliary memorymeans in the color address corresponding to the output at the instant,the comparator providing an output of one of a positive test signal whenthe color change signal corresponds to the reference signal and of anegative test signal when the color change signal does not correspond tothe reference signal; an address counter for the auxiliary memory means;incrementing means responsive to the comparator means for providing anoutput to the address counter of the auxiliary memory means, theincrementing means incrementing the said address counter in response toa negative test signal, the auxiliary memory means providing at one ofthe reading outputs thereof an operand signal when a positive testsignal is obtained for the color address corresponding to such output,the operand signal controlling the main memory means so that a tracecorresponding to the data contained at the corresponding address in themain memory means is effected on the screen.
 7. Visual display assemblyaccording to claim 6, wherein the reference element means is a countercapable of changing states for each cycle of traces in accordance withthe number of colors in each of the cycles.
 8. Visual display assemblyaccording to claim 7, wherein the incrementing means includes an ANDgate having one input connected to the output of the comparator meansand another input connected to receive clock pulses.
 9. Visual displayassembly according to claim 5, wherein the color change address sortingout system means comprises: reference element means for providingsuccessive outputs for each cycle of traces and for each of the colorsof a reference signal characteristic of the color; color comparatormeans for comparing, at each instant, the reference signal with a colorchange signal provided at one of the outputs of the auxiliary memorymeans, the color change signal being characteristic of the color changedata existing in the auxiliary memory means in the color addresscorresponding to the output at the instant, the comparator providing anoutput of one of a positive test signal when the color change signalcorresponds to the reference signal and of a negative test signal whenthe color change signal does not correspond to the said referencesignal; an address counter for the auxiliary memory means; incrementingmeans responsive to the comparator means for providing an output to theaddress counter of the auxiliary memory means, the incrementing meansincrementing the said address counter in response to a negative testsignal, the auxiliary memory means providing at one of the readingoutputs thereof an operand signal when a positive test signal isobtained for the color address corresponding to such output, the operandsignal controlling the main memory means so that a trace correspondingto the data contained at the corresponding address in the main memorymeans is effected on the screen.
 10. Visual display assembly accordingto claim 9, wherein the reference element means is a counter capable ofchanging states for each cycle of traces in accordance with the numberof colors in each of the cycles.
 11. Visual display assembly accordingto claim 10, wherein the incrementing means includes an AND gate havingone input connected to the output of the comparator means and anotherinput connected to receive clock pulses.
 12. Graphic visual displayassembly comprising: polychromatic cathode tube means for displaying apicture composed of traces of various colors in accordance with binarydata items supplied by a computer in groups of data items, each groupdefining successive traces having the same color; main memory means forrecording the groups of data items at successive groups of addresseswherein the first address is the color data item of the correspondingtraces; processing unit means responsive to the main memory means forgenerating signals for controlling the cathode tube means in accordancewith data read-out from the main memory means; and selection circuitmeans for sequentially selecting one of the various colors and forcontrolling the read-out from the main memory means of all the groups ofdata items preceded by the color data item of the selected color, thedata read-out being supplied to the processing unit means for enablingthe display, one color after another, of the traces having the samecolor to form a composite picture.
 13. A visual display assemblyaccording to claim 12, wherein the selection circuit means includes anauxiliary memory means for recording the color addresses and recordingthe corresponding color data.
 14. A visual display assembly according toclaim 13, wherein the selection circuit means also includes colorsorting means for controlling the auxiliary memory means to sort out theaddresses in the suxiliary memory means which contain identical colordata at the reading outputs of the auxiliary memory means and forcontrolling the reading inputs of the main memory means in accordancetherewith.